Uncertainty Principle
by DnKS-giRLs
Summary: A can-be-seen-as-D18 fic. Quantum physics and mafia member really did not match. Or at least, Dino Cavallone thought so. And his feeling when somehow he was involved in a talk about said subject with Gokudera could only be described as extreme confusion.


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**Title:** Uncertainty Principle

**Author:** DnKS - giRLs

**Rating:** PG

**Pairing:** D18

**Disclaimers:** we hereby declare that we hold no claim over Katekyo Hitman Reborn and all its characters. This disclaimer shall be our way of acknowledging the original author and creator of the aforementioned title.

**Warning:** …(lame explanation of) quantum mechanics in a fanfiction.

**Note:** we are by no means experts in the field of physics so we apologize for any error you might spot in this fanfiction.

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To speak in all honesty, Dino Cavallone never predicted that he would run to Gokudera Hayato when he visited Namimori High that day. Neither did he predict that his simple accidental meeting would turn up into a lengthy discussion about things so very beyond him, things that normal high school kids called physics.

It all started when he entered the gates of Namimori High that afternoon. It was not the first time he graced that high school building with his presence. His position as Hibari Kyouya's tutor gave him a nice excuse for visiting Namimori High every time he wanted under the pretence of seeing his supposedly protégé. And indeed, that was his initial reason why he came to that place that afternoon, only to bump with Gokudera Hayato on the hallway.

Dino had known Gokudera before. After all, being part of a famiglia meant that he would at the very least be aware of the members of his or other famiglia. Mafia world was so interconnected with webs that spelled cunningness, betrayal, loyalty, and blood. So, yes, he indeed knew Gokudera Hayato though he could say they had never had any decent heart to heart conversation before. But that day, it was about to change.

The Namimori High Disciplinary committee was still in the middle of a meeting when Dino arrived at the school. So when he happened to cross path with Gokudera and the other boy seemed like for once willing to stand his presence, he had asked the young Guardian to accompany him.

He was a bit surprised when Gokudera agreed to his proposition.

They moved to the currently unused music room where a grand piano was sitting innocently in the middle of it. Seeing that, Dino was reminded about certain information he knew regarding Gokudera Hayato, certain information which said that the boy used to play the piano in the past. Considering that, it was safe for him to assume that Gokudera brought him to the room simply because he needed to practice his art, but his naive thought was easily thwarted when, instead of playing the piano, Gokudera Hayato began talking about something so far away from his initial prediction.

He began talking about quantum physics.

It began innocently enough, with Gokudera spoke up, "It's a curious thing, that cracky Bazooka that stupid cow always brings along with him."

"The ten years later bazooka?" he asked, intrigued at what might have prompted Gokudera to talk about it.

"Yeah, that," Gokudera said with an almost disinterested air. "You ever heard of quantum physics?"

Dino blinked, "Hm?"

"Quantum physics, quantum mechanics, quantum leap, whatever," Gokudera proceeded, seemed not to heed Dino's response whatsoever. "You do know it, right?"

"Uh..." Dino said. He had long since left his good old school days and even when he was still forced by his father to attend class, physics was the subject that he was weakest at. But thankfully, there was television. "You mean the TV series of 'Quantum Leap' or the physics term one?"

"The physics one, of course!" Gokudera spat, diminishing any hope, however small, from Dino's mind that they would just simply have a light chit-chat about the episodes of some old TV series. "I always wonder about the principle applied in making that damn bazooka. I mean, when you get shot, you swapped place with your ten years later self, right?"

Now that was a question Dino could answer. "Yes."

"Basically, travelling through time is a tricky subject," Gokudera said. "No, maybe I should call it closed time like curves which allows people to return to their own past but still, it's kinda contradictory."

"Uh..." Dino mumbled with his mind already suffered the initial state of confusion.

"Travelling to the future is perhaps more explainable with the theory of relativistic velocity," Gokudera mused and somehow Dino felt a bit annoyed that his companion suddenly seemed way smarter than him. "But backwards time travel is highly unlikely considering the causality issues. Yet if we are using the idea of branching parallel universe, where the past is not really the past but only an instance of past from another world parallel to yours, then maybe it can be achieved. But what principle is used in that fucking bazooka I don't know and damn, it's driving me mad trying to figure things out!"

Dino only blinked and watched in mixed fear and confusion as Gokudera continued his ranting.

"I mean, hell, I don't even know if I'm allowed to kill someone or not when that darn bazooka transports me to... I don't know, my future or my past, and it creeps me out!"

"What creeps you out?" Dino asked.

"This whole to-kill-or-not-to-kill issue," Gokudera said. "Say, if I'm transported to my past and I managed to kill someone who, it turned out later, had an important role in my creation, I don't know, like... what if I kill my parents? That means I wouldn't have been born, right? Then what would happen to me?"

Dino frowned. As far as he knew, the Bovino famiglia only made the ten years old later bazooka to transport one person to the future. "I don't think it's possible for you to kill your grandfather in the past."

"Ah, so you're also the follower of Novikov self-consistency conjecture," Gokudera said, pointing at him and Dino could only think 'Novi who?. "But if it is so, then how could you explain this whole future shit? I mean, when those people... us, well, from my side... you know, when they come from the future, they tell things that happened in the future, right? And so far what they told us has always been consistent. Even their selves are also consistent. So, maybe we can say that time line is flexible and is subject to change and... holy shit fucking hell, I can make a PhD. thesis from this!"

"Well..." Dino said hesitantly since he did not quite know how to respond to that.

"But then... if we are to say that the future is indeed our future... hum... it's pretty complicated..." Gokudera mused as he scratched his head and Dino began to think if the boy had once again being subjected to his dear sister's venomous cooking for two apparent reasons. First, he had not yet thrown any harsh remark or curse word at him. And second, he managed to appear intelligent for more than five minutes. Something had to be really wrong with the boy and Dino could not decide if he liked the change or not.

"What is complicated?" he asked.

"Let's say that the future is indeed our future, I mean, nothing about that parallel universe shit or any of that 'history-is-fixed-and-cannot-be-changed' crap," Gokudera said wistfully. "So when your self from the future say that an event will occur in ten years from now, it's highly possible that it will indeed happen."

Dino thought for a while. "I see..."

"So, if your future self say that someone you trust the most in the present will betray you and even... I don't know, kill all the members of your famiglia, will you still trust that person or will you destroy him once and for good?" Gokudera asked. "Or if your future self say that someone you think as an ordinary person will turn out as your greatest enemy in the future, will you kill that guy to avoid having him as enemy in the future?"

"I never... thought about that, actually," Dino said, his mind was already thinking hard about the question that Gokudera had just said.

"Well, theoretically if you kill that person then you won't have him as your enemy in the future, right? But can we really change the future? Or maybe is it our doing, by trying to kill that person who's supposed to be our future enemy, which makes him be our enemy at the first place. This whole thing made me confused and I don't like it," Gokudera talked rapidly. "Fuck, this is all that stupid cow's fault, him and that stupid bazooka of his! If only he were a bit more intelligent I'd have discussed this with him but his brain if even smaller than a shrimp!"

Dino blinked even more rapidly than before. For once he was thankful that he wore his digital watch so he could make some excuse to leave Gokudera's company, saying that the meeting would probably have ended by then and he needed to see Hibari before something bad happened. It was not really a lie. He knew something bad would really happen if he kept being in Gokudera's company and it was not solely due to any grievous bodily harm that Hibari might give him if he showed up late for their appointment.

He sighed as he walked across the corridor. Physics always gave him nightmare during his high school days and it seemed that certain subject still did not lose its power to make him feel the exact definition of dread every time he was being faced with said subject. He managed to get somewhat acceptable grade during his school's days but he knew it was his least interest to come in contact with anything that remotely smelled like physics, or math, or history, or any boring subjects that his teachers somehow had managed to force on him. Being in the world of mafia had lulled him in false sensation of security that he would not be expected to see concepts like integrals or exponential functions or anything of the kind. People did not try to measure the momentum when they were about to kill somebody. People did not try to consider the probability function when they shoot their enemies.

But now, he sighed, quantum physics?

Though he admitted that he only understood less than one third of Gokudera's intellectual rambling, he did manage to catch the last question the young guardian had thrown him. And it was that certain question that troubled his mind as he trod his way inside the many interconnecting corridors of Namimori High. It was that certain question that still troubled his mind when he finally faced his supposedly protégé.

Hibari Kyoya, as usual, had a scowl on his face that was apparent ever since the first moment Dino entered the room. The scowl was a usual occurrence, but the narrowing of eyes that was without doubt directed to him made Dino wince.

Hibari Kyoya was annoyed. At him.

"Um, nice weather today," he began in vain hope that Hibari would find more pleasure in admiring the weather than to bite him to death. Yeah, really vain hope there, Dino could even feel all his ancestors laughing at him from their graves.

"You're late," Hibari stated. "By five minutes."

Somehow Dino knew that trying to defend himself by saying things like 'Awh, come on, Kyoya, it's only five minutes' would do him nothing good so he only gave his trademarked sheepish smile.

"I was... uh... bumping into Gokudera Hayato on my way here, and you were still in your meeting so..." he gulped. "I had a chat with him while waiting for your meeting to finish..."

Hibari's eyes narrowed even further. "Crowding?"

Dino shook his head frantically. "No. It's only the two of us... er, I mean..."

"Crowding," Hibari flatly declared, dismissing any words that Dino might say.

"Uh, well, if you say so..." Dino said. He wondered why it was that he always had an urge to rub the back of his neck whenever Hibari spoke to him in that tone. "Anyway, we had this discussion about that... er, ten years later bazooka..."

A mere sideway glare was thrown to his direction but it was enough indication for Dino that he could continue his explanation. He cleared his throat.

"Yeah, so… the bazooka can swap you with your ten years old later self, so… uh, if you from ten years later say something will happen in the future, you can believe him that it will indeed happen, right?" Dino said somewhat rapidly. "I mean, if someone, uh, how to say this… if someone from the future say that a certain person will be your enemy will you get rid of that person or not? And… uh, I don't know, but we were also talking about something like parallel universe or whatever principle, but…"

He took a breath. He knew he was rambling like an idiot and he wondered why Hibari had not yet ordered him to shut up.

"If someone from the future say that I will betray you and be your enemy, will you believe him and will you try to destroy me?"

There was a halt in the air, he could feel it. Hibari stared right at him, and then he could see the young boy snorted.

"You won't betray me," he said easily, dismissively, clearly, as if he had no doubt on the matter.

"But…" Dino started. There was a sense of pride in him in thinking that maybe Hibari trusted him enough until he could say that, but he knew never to get his hope high around his dangerous protégé. "If someone from the future…"

"I believe no one," Hibari cut him off in the middle of his sentence. "And you won't betray me. You can't. I won't let you."

Dino Cavallone stared at the one who had just said those words. He allowed a look of astonishment to grace his face for a while before he burst out chuckling. It was just like Hibari Kyoya, he thought, to dismiss his question like that. And it was just like Hibari Kyoya, he mused fondly, to calm his somewhat worried and confused mind down with his words, no matter how sharp and harsh they might sound.

He reclined himself to one of the chairs situated in the room, feeling glad somehow, and relieved. He might not know a thing about quantum physics or whatever, but he trusted Hibari Kyoya. And so with that consideration in his mind, he dismissed any thought concerning quantum physics or ten years old bazooka or whatever and opted to do a far more enjoyable thing by watching Hibari, his stubborn and prideful Hibari Kyoya, until the boy snapped at him and let Dino know that his threat of biting him to death was not merely empty words.

- end -

(A/N: thank you for sparing your time to read this story. If you got a hard time reading and trying to understand the whole quantum principle, then… could it be of any consolation if we admit that we also got some hard time trying to explain it and write it down? Guess not… anyway, we wish to hear your comment on this story so, like always, reviews would be very much appreciated.)


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